Abstract / Summary. In Cameroon the HIV epidemic is generalized with an estimated prevalence of 5.1%, and characterized by a very high genetic diversity. Indeed, to date the epidemic is driven by all HIV subtypes including circulating recombinant forms (CRF), unique recombinant forms (URF), and highly divergent strains such as groups O, and N and P. The impact of the high diversity on the emergence of HIV drug resistance in Cameroon has not been well studied. In 2010, the coverage of the PMTCT was 22.2% with 16.0% of infected children receiving antiretroviral treatment nationwide. Limited studies in Cameroon reported primary resistance-associated mutations among antiretroviral therapy (ART) drug-nave persons, mainly to reverse transcriptase (RT) and protease inhibitors. The Cameroon Baptist Convention Health Board (CBCHB) currently supports 427 sites all over the country for the Prevention of Mother-to-Child Transmission (PMTCT) program, of which 240 are government facilities. To date, CBCHB has counseled 450, 231 women and tested 428, 370 (95.1%) at these facilities (with an HIV prevalence of 10.7%). Thanks largely to the CBCHB efforts, maternal and infant ART uptake rates have increased in Cameroon from 37.7% in 2000 to 96.6% in 2009. The goal of this study is to determine the prevalence of drug-resistant HIV among children < 18 months of age, and also evaluate the impact of the enormous HIV genetic diversity on the occurrence of drug-resistant mutations in PMTCT programs in Cameroon. Leftover dried blot spot specimens collected originally for early infant diagnosis will be used in this study. The outcome of this study will assist decision-making on first-line antiretroviral drug regimens for the PMTCT program in Cameroon and will provide a better understanding of the association of the extensive HIV genetic diversity and occurrence of resistant mutations. It will also contribute to the global effort to respond to the emergence of HIV drug resistance.